They're okay. Lots of rote tasks throughout the civ franchise, the impact of eurekas on #inputs game to game is tiny and it gives you an extra element to how tech progresses. Compare this to something like the poorly managed trade routes UI, diplomatic UI making deals, city management (a travesty compared to even just Civ 4, which had its own issues), or even simple unit movement and it's a blip on the radar at worst in terms of input burden. On the flip side, you do have to plan around a bit more when it comes to progressing tech, and at least in principle rival civs could seek to deny you some of them and take advantage. As such they're not bad from a mechanic design perspective, even if the game's limitations and some of them not being very creative/well-placed doesn't allow them to completely shine.